Cylinder-head for gas-engines.



CGLELLAND 6: W. l LE. 'CYLINDER' HEADTOR GAS ENG S.

APPLICATION PIL BD MAB.. 13, 1909 K -Pantentd-Jan. 6, 1'914.

TENT OFFICE.

EDWARD S. MUCLELLAND AND WILLIAM A. BOLE, OF PITTSBURGH, PENNSYLVANIA,

ASSIGNORS, BY MESNE ASSIGNMENTS, TO THE coLoaIAL TRUST COMPANY, TRUS- TEE, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION 0F PENNSYLVANIA.'

CYLINDER-HEAD FOR GASENGINES.

i ,cesante Specification of Letters Patent.

Patented Jan. 6, 1914.

Application filed March 13, 1909. Serial No.'483,131.

lie it. known that we, lniviiiin tw. Methan,- LAND and Wiiiitiiiii A. Bonn, citizens of the United States, and residents of `littslntrgh, county of Allegheny, and State of lenusyh vani-a, have iiiade a new and useful Invention in (yliuder-lleads for Gas-Engines, of which the followingl is a specification.

This invention relates to cylinder heads and particularly to cylinder heads of motors in which an exploded charge is eniployed to develop power. lyliiitler heads of explosion `motors are usually constructed with a water cliaiiiher iu which a current of water is caused to circulate so as to absorb and carry oil' the heat generated by the ex plotled charges in the iffonibustion chamber of the n'iotor cylinder. These cylinder heads are produced by casting methods and those through which the piston rods pass are generally in the form of two tubes spaced apart to form a water chamber, the respective ends of the tubes being connected by diaphragiiis or webs, In casting the heads, holes or openings are formed in `one of they-diaphragins to provide means whereby the gases set up by pouring the metal in the mold may be permitted to escape from that part of the core which forms the water chamber. These holes are also useful in affording means whereby the sand core for the water chaniber may be removed. lt hasbeeii found in practice that a head formed as just described is liable to crack or bruik during service. In some instances the heads have been known to crack near the juncture of the inner tube with the inner diaphragm. At other times the heads have broken or pulled away at points adjacent to the cored holes -from which the gases and sand escape. In other words the cracking lakes place atthe Weakest point in the hcad.- The reason for this breaking or cracking may be eX- plained as follows: After the casting is poured, the heads are withdrawn from the flasks in order that the flasks ii'iay be uscd again. The cores, however, remain in the casting because they cannot conveniently be removed until the casting cools somewhat. As the castings are dragged from the flasks the outer surface of the head will be exposed to the atmosphere, causing rapid radiation of heat therefrom with resultant rapid cooling of that portion. The sand core in the water space and the core'for the gland through which the piston rod passes will. act as insulators for the inner tube of the head and prevent its rapidly cooling. AS a result of this, the outer tube will contract and become set before the inner tube can do so. At a later period, when'the inner tube begins to contract it finds itself conned and resisted by tl'ic outer tube to which it is tied at both ends by the diaphragms. As the inner tube continues to cool and shorten, stresses are set up in both tubes,- tension .stresses in the cooling tube and compression stresses in the cold-er member. These contlicting' internal stresses weaken the casting and diminish its capacity to withstand stresses from without. In order to express our idea clearly, we may call the strength of the outer tube as A, and that of the inner tube B, but on account of these acting in a contradictory or opposed manner the con'ibincd strength for regular duty is not A+B but rather A*B,' assuming that A isA greater than B. rlhe tendency of the inner tube to pull away from the parts to which it is anchored frequently results in the head "cracking at a point adjacent either the inner web (that is the one within the combustion chamber) or the outer web.

Ono of the objects of our invention is to provide a head which will be free or prac tically free from internal strains or stresses due to casting or from other causes.

3y constructii'ig a casting in accordance with our invention the inner and outer tubes of the head may be permitted to contract or cool independently of each other without any discordanteffects. t

According to one approved form of our invention the casting is made so that th.. inner and outer tubes are connected together by the diaphragm at one end only,

the remainingl ends of the tubes being free so that during the cooling process the ir1 ner and outer tubes may independently shorten as they cool and 1n such a manner that .the contraction of one tube will have no deleterious effect on the other,

ln order to convey a comprehensive idea. of one form of our invention 'we have illustratcd it in the acconipanying dra-wings, ,in which,

Figure l is a vertical longitudinal sectional view through a cylinder head with a being merely shown diagrammatically, and,

- form a water chamber S. The casting is pro- .piston rod packing designated 1Q,I said pisf the end of the tube 5 may be drawn to the piston rod in place, the packing which is usually employed with'these piston heads Fig. 2 is an end view of the piston head.

Referring nowto the drawings` bynumerals of reference, 5 designates the outer tube of the cylinder head, 6 the inner tube thereof, and 7 the diaphragm for connecting the inner and outer tubes together and which in' connection with the inner and outer tubes vided with a central opening 9 through which the piston rod 10 of any approved construction may reciprocate and the casting may be provided with a seat 11 for a ton rod packing being of suitable form and material. By reference to Fig. 1 it will be observed that the outer ends of the tubes 5 and (3 are spaced away from each other by a circumferential slot or annulus.

13 designates a closing ring which is provided with a reduced portion 14 to tit into the annulus and close the' slot between the inner and outer tubes after the casting has i been machined. The ring 13 may be fasl tened in place by the fastening devices 1:5 t

f tubes, means integral with said tubes and projecting through a ange in the ring and entering a portion of the tube 5. Similar fastening devices 1G are provided for securing the ring 13 to the tube G. The head may I be attached to the cylinder 17 by fastening devices 1S which pass through the tiange 19 l on the cylinder head and enter the cylinder' 17. The water chamber 8 is provided with l a supply port 90 which passes through the ring 13 and inte the chamber 8. A similar 5 port Q1 serves as an outlet port for the?` chamber 8 and this port 2l likewise is shown 1 as passing through the ring' 13. The pacl'- i ing 12 may be secured in place by the guard i ring QQ held to the ring 13 by the fastening i devices 1G.

When the casting is made the tubes 5 and i G 'are cast so that one end of cach tube is t free oi the other and heretofore ex@ plaincd this enables the respective tubes to 1 contract and expand independently of each other, and one without atfecting the other. In actual practice we preterto machine the l ring 13 so that the ange 23 of the ring 13 will be slightly spaced away from the liange 19 of the outer tube 5 when the flange 24 is seatedon the tube G. Then by manipulating the fastening and tension devices 15 iiange 23 of the ring 13. so as to put the tube 5 under slight tension and the inner tube under slight conirgession (whereby the inner diaphragm i' will be slightly dished as shown in dotted lines) so that when the engine is in actual service and the'outer and more exposed portion of the head, viz., tube 5, shall be heated up to a higher temperature than the inner and more protected tube G, the dilation ot the outer tube shall tend to remove all internal stresses in the cylinder head and the consti-notional elements ot' the cylinder head may all act in harmony to afford adequate resistance to the stresses due to pressure within the cylinder. Then thus constructed, it the strength ot the outer wall. or tube 5 is expressed by A and the strength of the inner wall or tube 6 be expressed by B, the strength of the entire head is equal to A-l-B, and the head thus constructed and free from the internal strains due to former methods of' design will be more dependable and reliable.

lt is obvious that our invention may partake of forms other than that shown in the drawing without departing from the spirit of the invention or sacrificing any of the advantages thereof.

that we claim is: 1. A cylinder head casting comprising two connecting them together, and means for putting one of the tubes under tension.

2. A cylinder' head casting comprising two tubes connected together at one end and spaced apart at the other, and means connecting the spaced end of one tube to the spaced end ot the other tube to flex the rst mentioned connection.

3. A cylinder head casting comprising an outer tube and an inner tube. a web connecting the inne'r end of the respective tubes. and a removable connection for the outer free ends of said tubes and for flexing said web.

4. A cylinder head comprising an outer tube and an inner tube. one of these being longer than the other, a. web integral with and connecting the inner ends ot respective tubes, the outer ends of respective tubes being tree. and means for connecting the outer free ends of said tubes and to put one of said tubes under tension.

In testimony whereof, we have hereunto subscribed our names this 11th day of March, 1909.

EDYVARD S. MCCLELLAND. WILLIAM A. BOLE.

lVitnesses:

CHARLES `W. MCGHEE, C. W. BALLAY. 

